Capillary tube for a packaged terminal air conditioner unit

ABSTRACT

A capillary tube for a heat pump system, such as a packaged terminal air conditioner unit, includes features for adjusting a restriction on a flow of refrigerant through the capillary tube depending upon a direction of the flow of refrigerant through the capillary tube. A related packaged terminal air conditioner unit is also provided.

FIELD OF THE INVENTION

The present subject matter relates generally to heat pump systems, such as packaged terminal air conditioner units, and capillary tubes for the same.

BACKGROUND OF THE INVENTION

Certain heat pump systems include a sealed system for chilling and/or heating air with refrigerant. The sealed systems generally include a throttling device for restricting a flow of refrigerant between an outdoor coil and an indoor coil of the sealed system. Various throttling devices are available, including capillary tubes, J-T valves, electronic expansion valves, etc. Electronic expansion valves can offer functional advantages over other throttling devices. In particular, electronic expansion valves can be adjusted to vary the restriction on refrigerant flowing through the electronic expansion valves.

Packaged terminal air conditioner units generally include a casing and a sealed system. Due to space constraints within the casing, selection of sealed system components for packaged terminal air conditioner units can be limited. For example, electronic expansion valves can be bulky and occupy a large volume within the casing. Thus, utilizing electronic expansion valves within packaged terminal air conditioner units can be difficult despite functional advantages provided by electronic expansion valves. Electronic expansion valves can also be costly.

Accordingly, a packaged terminal air conditioner unit with features for providing variable restriction on refrigerant flowing through a throttling device of the packaged terminal air conditioner unit would be useful. In particular, a packaged terminal air conditioner unit with a throttling device that includes features for providing variable restriction on refrigerant flowing through the throttling device that also occupies little space within a casing of the packaged terminal air conditioner unit would be useful.

BRIEF DESCRIPTION OF THE INVENTION

The present subject matter provides a capillary tube for a heat pump system, such as a packaged terminal air conditioner unit. The capillary tube includes features for adjusting a restriction on a flow of refrigerant through the capillary tube depending upon a direction of the flow of refrigerant through the capillary tube. A related packaged terminal air conditioner unit is also provided. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.

In a first exemplary embodiment, a packaged terminal air conditioner unit is provided. The packaged terminal air conditioner unit includes a casing that extends between an exterior side portion and an interior side portion. A compressor is positioned within the casing. The compressor is operable to increase a pressure of a refrigerant. An interior coil is positioned within the casing at the interior side portion of the casing. An exterior coil is positioned within the casing at the exterior side portion of the casing. A reversing valve is in fluid communication with the compressor in order to receive compressed refrigerant from the compressor. The reversing valve is configured for selectively directing the compressed refrigerant from the compressor to either the interior coil or the exterior coil. A capillary tube extends between the interior coil and the exterior coil in order to direct refrigerant between the interior coil and the exterior coil. The capillary tube includes means for adjusting a restriction on a flow of refrigerant through the capillary tube depending upon a direction of the flow of refrigerant through the capillary tube.

In a second exemplary embodiment, a packaged terminal air conditioner unit is provided. The packaged terminal air conditioner unit includes a casing. A compressor is positioned within the casing. The compressor is operable to increase a pressure of a refrigerant. A reversing valve is positioned within the casing. The reversing valve is in fluid communication with the compressor in order to receive compressed refrigerant from the compressor. An interior coil is positioned within the casing. An exterior coil is positioned within the casing opposite the interior coil. The interior coil and the exterior coil are in fluid communication with the reversing valve such that either the interior coil or the exterior coil receives the compressed refrigerant from the reversing valve. A capillary tube extends between the interior coil and the exterior coil in order to direct refrigerant between the interior coil and the exterior coil. The capillary tube extends between a first end portion and a second end portion. The first end portion of the capillary tube is positioned adjacent the exterior coil. The second end portion of the capillary tube is positioned adjacent the interior coil. The capillary tube defines an interior volume for directing the flow of refrigerant through the capillary tube. A block is positioned within the interior volume of the capillary tube at the first end portion of the capillary tube such that the block occupies a portion of the interior volume of the tubular body at the first end portion of the tubular body.

In a third exemplary embodiment, a capillary tube for a heat pump system is provided. The capillary tube includes a tubular body extending between a first end portion and a second end portion. The tubular body defines an interior volume for directing a flow of refrigerant through the tubular body. Cross-sections of the interior volume of the tubular body are substantially constant between the first and second end portions of the tubular body. A block is positioned within the interior volume of the tubular body at the first end portion of the tubular body such that the block occupies a portion of the interior volume of the tubular body at the first end portion of the tubular body.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

FIG. 1 provides an exploded perspective view of a packaged terminal air conditioner unit according to an exemplary embodiment of the present subject matter.

FIG. 2 provides a schematic view of certain components of the exemplary packaged terminal air conditioner unit of FIG. 1.

FIG. 3 provides a perspective view of a capillary tube according to an exemplary embodiment of the present subject matter.

FIG. 4 provides a perspective view of a capillary tube according to an additional exemplary embodiment of the present subject matter.

FIG. 5 provides an exploded perspective view of a capillary tube according another exemplary embodiment of the present subject matter.

FIG. 6 provides a perspective view of a capillary tube according still another exemplary embodiment of the present subject matter.

FIG. 7 provides a perspective view of a capillary tube according yet another exemplary embodiment of the present subject matter.

FIGS. 8 and 9 provide partial section views of the exemplary capillary tube of FIG. 7 and a flow washer of the exemplary capillary tube.

FIG. 10 provides a section view of a capillary tube according yet another additional exemplary embodiment of the present subject matter.

FIGS. 11 and 12 provide schematic views of a capillary tube according still another additional exemplary embodiment of the present subject matter.

FIG. 13 provides a perspective view of a capillary tube according an additional exemplary embodiment of the present subject matter.

FIGS. 14 and 15 provide section views of the exemplary capillary tube of FIG. 13.

FIGS. 16 and 17 provide section views of the exemplary capillary tube of FIG. 13 in another exemplary embodiment.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

FIG. 1 provides an exploded perspective view of a packaged terminal air conditioner unit 100 according to an exemplary embodiment of the present subject matter. Packaged terminal air conditioner unit 100 is operable to generate chilled and/or heated air in order to regulate the temperature of an associated room or building. As will be understood by those skilled in the art, packaged terminal air conditioner unit 100 may be utilized in installations where split heat pump systems are inconvenient or impractical. As discussed in greater detail below, a sealed system 120 of packaged terminal air conditioner unit 100 is disposed within a casing 110. Thus, packaged terminal air conditioner unit 100 may be a self-contained or autonomous system for heating and/or cooling air.

As may be seen in FIG. 1, casing 110 extends between an interior side portion 112 and an exterior side portion 114. Interior side portion 112 of casing 110 and exterior side portion 114 of casing 110 are spaced apart from each other. Thus, interior side portion 112 of casing 110 may be positioned at or contiguous with an interior atmosphere, and exterior side portion 114 of casing 110 may be positioned at or contiguous with an exterior atmosphere. Sealed system 120 includes components for transferring heat between the exterior atmosphere and the interior atmosphere, as discussed in greater detail below.

Casing 110 defines a mechanical compartment 116. Sealed system 120 is disposed or positioned within mechanical compartment 116 of casing 110. A front panel 118 and a rear grill or screen 119 are mounted to casing 110 and hinder or limit access to mechanical compartment 116 of casing 110. Front panel 118 is mounted to casing 110 at interior side portion 112 of casing 110, and rear screen 119 is mounted to casing 110 at exterior side portion 114 of casing 110. Front panel 118 and rear screen 119 each define a plurality of holes that permit air to flow through front panel 118 and rear screen 119, with the holes sized for preventing foreign objects from passing through front panel 118 and rear screen 119 into mechanical compartment 116 of casing 110.

Packaged terminal air conditioner unit 100 also includes a drain pan or bottom tray 138 and an inner wall 140 positioned within mechanical compartment 116 of casing 110. Sealed system 120 is positioned on bottom tray 138. Thus, liquid runoff from sealed system 120 may flow into and collect within bottom tray 138. Inner wall 140 may be mounted to bottom tray 138 and extend upwardly from bottom tray 138 to a top wall of casing 110. Inner wall 140 limits or prevents air flow between interior side portion 112 of casing 110 and exterior side portion 114 of casing 110 within mechanical compartment 116 of casing 110. Thus, inner wall 140 may divide mechanical compartment 116 of casing 110.

Packaged terminal air conditioner unit 100 further includes a controller 146 with user inputs, such as buttons, switches and/or dials. Controller 146 regulates operation of packaged terminal air conditioner unit 100. Thus, controller 146 is in operative communication with various components of packaged terminal air conditioner unit 100, such as components of sealed system 120 and/or a temperature sensor, such as a thermistor or thermocouple, for measuring the temperature of the interior atmosphere. In particular, controller 146 may selectively activate sealed system 120 in order to chill or heat air within sealed system 120, e.g., in response to temperature measurements from the temperature sensor.

Controller 146 includes memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of packaged terminal air conditioner unit 100. The memory can represent random access memory such as DRAM, or read only memory such as ROM or FLASH. The processor executes programming instructions stored in the memory. The memory can be a separate component from the processor or can be included onboard within the processor. Alternatively, controller 146 may be constructed without using a microprocessor, e.g., using a combination of discrete analog and/or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software.

FIG. 2 provides a schematic view of certain components of packaged terminal air conditioner unit 100, including sealed system 120. Sealed system 120 generally operates in a heat pump cycle. Sealed system 120 includes a compressor 122, an interior heat exchanger or coil 124 and an exterior heat exchanger or coil 126. As is generally understood, various conduits may be utilized to flow refrigerant between the various components of sealed system 120. Thus, e.g., interior coil 124 and exterior coil 126 may be between and in fluid communication with each other and compressor 122.

As may be seen in FIG. 2, sealed system 120 also includes a reversing valve 132. Reversing valve 132 selectively directs compressed refrigerant from compressor 122 to either interior coil 124 or exterior coil 126. For example, in a cooling mode, reversing valve 132 is arranged or configured to direct compressed refrigerant from compressor 122 to exterior coil 126. Conversely, in a heating mode, reversing valve 132 is arranged or configured to direct compressed refrigerant from compressor 122 to interior coil 124. Thus, reversing valve 132 permits sealed system 120 to adjust between the heating mode and the cooling mode, as will be understood by those skilled in the art.

During operation of sealed system 120 in the cooling mode, refrigerant flows from interior coil 124 flows through compressor 122. For example, refrigerant may exit interior coil 124 as a fluid in the form of a superheated vapor. Upon exiting interior coil 124, the refrigerant may enter compressor 122. Compressor 122 is operable to compress the refrigerant. Accordingly, the pressure and temperature of the refrigerant may be increased in compressor 122 such that the refrigerant becomes a more superheated vapor.

Exterior coil 126 is disposed downstream of compressor 122 in the cooling mode and acts as a condenser. Thus, exterior coil 126 is operable to reject heat into the exterior atmosphere at exterior side portion 114 of casing 110 when sealed system 120 is operating in the cooling mode. For example, the superheated vapor from compressor 122 may enter exterior coil 126 via a first distribution conduit 134 that extends between and fluidly connects reversing valve 132 and exterior coil 126. Within exterior coil 126, the refrigerant from compressor 122 transfers energy to the exterior atmosphere and condenses into a saturated liquid and/or liquid vapor mixture. An exterior air handler or fan 150 is positioned adjacent exterior coil 126 may facilitate or urge a flow of air from the exterior atmosphere across exterior coil 126 in order to facilitate heat transfer.

Sealed system 120 also includes a capillary tube 128 disposed between interior coil 124 and exterior coil 126, e.g., such that capillary tube 128 extends between and fluidly couples interior coil 124 and exterior coil 126. Refrigerant, which may be in the form of high liquid quality/saturated liquid vapor mixture, may exit exterior coil 126 and travel through capillary tube 128 before flowing through interior coil 124. Capillary tube 128 may generally expand the refrigerant, lowering the pressure and temperature thereof. The refrigerant may then be flowed through interior coil 124.

Interior coil 124 is disposed downstream of capillary tube 128 in the cooling mode and acts as an evaporator. Thus, interior coil 124 is operable to heat refrigerant within interior coil 124 with energy from the interior atmosphere at interior side portion 112 of casing 110 when sealed system 120 is operating in the cooling mode. For example, the liquid or liquid vapor mixture refrigerant from capillary tube 128 may enter interior coil 124 via a second distribution conduit 136 that extends between and fluidly connects interior coil 124 and reversing valve 132. Within interior coil 124, the refrigerant from capillary tube 128 receives energy from the interior atmosphere and vaporizes into superheated vapor and/or high quality vapor mixture. An interior air handler or fan 148 is positioned adjacent interior coil 124 may facilitate or urge a flow of air from the interior atmosphere across interior coil 124 in order to facilitate heat transfer.

During operation of sealed system 120 in the heating mode, reversing valve 132 reverses the direction of refrigerant flow through sealed system 120. Thus, in the heating mode, interior coil 124 is disposed downstream of compressor 122 and acts as a condenser, e.g., such that interior coil 124 is operable to reject heat into the interior atmosphere at interior side portion 112 of casing 110. In addition, exterior coil 126 is disposed downstream of capillary tube 128 in the heating mode and acts as an evaporator, e.g., such that exterior coil 126 is operable to heat refrigerant within exterior coil 126 with energy from the exterior atmosphere at exterior side portion 114 of casing 110.

Appropriate restriction of refrigerant within capillary tube 128 may assist with efficiently operating sealed system 120. However, the appropriate restriction may change depending upon whether sealed system 120 is operating in the cooling mode or the heating mode and the direction of refrigerant flow through capillary tube 128. As discussed in greater detail below, various features of capillary tube 128 may vary the restriction on refrigerant flowing through capillary tube 128 depending upon the direction of refrigerant flow through capillary tube 128.

As discussed above, when the refrigerant enters capillary tube 128, refrigerant is mostly or all liquid and is typically subcooled below the saturation temperature. The restriction of capillary tube 128 can directly correspond to the amount of vapor phase refrigerant within the flow of refrigerant through capillary tube 128 and/or the amount of subcooled liquid phase refrigerant within the flow of refrigerant through capillary tube 128. As the refrigerant flows through capillary tube 128, the refrigerant pressure decreases and refrigerant vapor bubbles form. Without wishing to be bound to any particular theory, the refrigerant vapor bubbles are of a much lower density than the liquid refrigerant and the refrigerant vapor bubbles displace liquid refrigerant and restrict mass flow. The present subject matter may assist with decreasing refrigerant mass flow in one direction, e.g., by increasing restriction of the refrigerant when the refrigerant is a vapor without having much of an effect when the refrigerant is a liquid flowing in the opposite direction.

It should be understood that sealed system 120 may include more capillary tubes between interior coil 124 and exterior coil 126 in alternative exemplary embodiments. For example, 120 sealed system 120 may include a pair of capillary tubes 128 plumbed in parallel between interior coil 124 and exterior coil 126. The pair of capillary tubes 128 may assist with more easily receiving refrigerant from when exterior coil 126 has two outlets and interior coil 124 has two inlets, in the cooling mode. In such exemplary embodiments, each capillary tube may have a different restriction in order to optimize or improve flow within interior coil 124 and/or exterior coil 126.

FIG. 3 provides a perspective view of a capillary tube 200 according to an exemplary embodiment of the present subject matter. Capillary tube 200 may be used in any suitable heat pump system. For example, capillary tube 200 may be used in packaged terminal air conditioner unit 100 as capillary tube 128 of sealed system 120 (FIG. 2). As discussed in greater detail below, capillary tube 200 includes features for adjusting a restriction on a flow of refrigerant through capillary tube 200 depending upon a direction of the flow of refrigerant through capillary tube 200.

As may be seen in FIG. 3, capillary tube 200 is a generally tubular body, such as a copper or aluminum pipe. Capillary tube 200 extends between a first end portion 202 and a second end portion 204. First end portion 202 of capillary tube 200 may be positioned adjacent and/or mounted to exterior coil 126 of sealed system 120. Second end portion 204 of capillary tube 200 may be positioned adjacent and/or mounted to interior coil 124 of sealed system 120. Capillary tube 200 also defines an interior volume 206, e.g., that extends between first and second end portions 202, 206 of capillary tube 200, for directing the flow of refrigerant through capillary tube 200.

Capillary tube 200 also includes a wire or block 210 positioned within interior volume 206 of capillary tube 200 at or adjacent first end portion 202 of capillary tube 200. Block 210 occupies a portion of interior volume 206 of capillary tube 200 at first end portion 202 of capillary tube 200. As may be seen in FIG. 3, interior volume 206 of capillary tube 200 may have a generally constant cross-sectional area between first and second end portions 202, 206 of capillary tube 200. By occupying the portion of interior volume 206 of capillary tube 200 at first end portion 202 of capillary tube 200, block 210 can adjust the restriction on the flow of refrigerant through capillary tube 200 depending upon a direction of the flow of refrigerant through capillary tube 200. For example, by occupying the portion of interior volume 206 of capillary tube 200 at first end portion 202 of capillary tube 200, the restriction on the flow of refrigerant when sealed system 120 is operating in the heating mode is greater than when sealed system 120 is operating in the cooling mode. In particular, refrigerant enters capillary tube 200 as a liquid and at least a portion of the refrigerant transforms to a vapor while passing through capillary tube 200. When vapor phase refrigerant passes through first end portion 202 of capillary tube 200, block 210 restricts refrigerant flow to a greater degree than when liquid phase refrigerant passes through first end portion 202 of capillary tube 200, e.g., due to the lower density of vapor phase refrigerant which can increase the velocity of the flow of refrigerant through capillary tube 200.

Block 210 may be constructed of or with any suitable material, e.g., that does not react with or corrode in the presence of the refrigerant within capillary tube 200. For example, capillary tube 200 and block 210 may be constructed with common materials, such as copper or aluminum. In alternative exemplary embodiments, capillary tube 200 and block 210 may be constructed with different materials.

Block 210 may be mounted to capillary tube 200 at first end portion 202 of capillary tube 200 in certain exemplary embodiments. Thus, block 210 may be static or fixed within capillary tube 200. For example, capillary tube 200 and/or block 210 may be bent at first end portion 202 of capillary tube 200 in order to hinder or limit movement of block 210 within interior volume 206 of capillary tube 200. As another example, block 210 may be brazed, glued or fastened to capillary tube 200 at first end portion 202 of capillary tube 200.

As may be seen in FIG. 3, capillary tube 200 defines a length L between first and second end portions 202, 204 of capillary tube 200. Block 210 may also define a length within interior volume 206 of capillary tube 200. The length of block 210 may be less than the length L of capillary tube 200. For example, the length of block 210 may be no greater than half the length L of capillary tube 200. As another example, the length of block 210 may be no greater than a quarter of the length L of capillary tube 200. As yet another example, the length of block 210 may be no greater than a tenth of the length L of capillary tube 200.

FIG. 4 provides a perspective view of a capillary tube 300 according to an additional exemplary embodiment of the present subject matter. Capillary tube 300 may be used in any suitable heat pump system. For example, capillary tube 300 may be used in packaged terminal air conditioner unit 100 as capillary tube 128 of sealed system 120 (FIG. 2). As discussed in greater detail below, capillary tube 300 includes features for adjusting a restriction on a flow of refrigerant through capillary tube 300 depending upon a direction of the flow of refrigerant through capillary tube 300.

Capillary tube 300 includes a generally tubular body, such as a copper or aluminum pipe. Capillary tube 300 may be constructed in the same or similar manner to capillary tube 200 (FIG. 4). Thus, capillary tube 300 extends between a first end portion 302 and a second end portion 304 and defines an interior volume 306 for directing the flow of refrigerant through capillary tube 300.

Capillary tube 300 also includes a crimp 310 defined by capillary tube 300 at or adjacent first end portion 302 of capillary tube 300. Crimp 310 is formed by capillary tube 300 such that crimp 310 reduces the cross-sectional area of interior volume 306 of capillary tube 300 at crimp 310. As may be seen in FIG. 4, interior volume 306 of capillary tube 300 may have a generally constant cross-sectional area between first and second end portions 302, 304 of capillary tube 300 except for crimp 310.

By reducing the cross-sectional area of interior volume 306 of capillary tube 300 at first end portion 302 of capillary tube 300, crimp 310 can adjust the restriction on the flow of refrigerant through capillary tube 300 depending upon a direction of the flow of refrigerant through capillary tube 300, e.g., in the same or similar manner to block 210 (FIG. 3) described above. For example, by reducing the cross-sectional area of interior volume 306 of capillary tube 300 at first end portion 302 of capillary tube 300, the restriction on the flow of refrigerant when sealed system 120 is operating in the heating mode is greater than when sealed system 120 is operating in the cooling mode.

Crimp 310 may be formed in any suitable manner on capillary tube 300. For example, a clamp or roller may plastically deform capillary tube 300 in order to form crimp 310 at first end portion 302 of capillary tube 300. Crimp 310 may be formed on capillary tube 300 such that crimp 310 extends uniformly about capillary tube 300 in certain exemplary embodiments.

As may be seen in FIG. 4, capillary tube 300 defines a length L between first and second end portions 302, 304 of capillary tube 300. Crimp 310 also defines a length CL on capillary tube 300. The length CL of crimp 310 may be less than the length L of capillary tube 300. For example, the length CL of crimp 310 may be no greater than a tenth of the length L of capillary tube 300.

FIG. 5 provides an exploded perspective view of a capillary tube 400 according another exemplary embodiment of the present subject matter. Capillary tube 400 may be used in any suitable heat pump system. For example, capillary tube 400 may be used in packaged terminal air conditioner unit 100 as capillary tube 128 of sealed system 120 (FIG. 2). As discussed in greater detail below, capillary tube 400 includes features for adjusting a restriction on a flow of refrigerant through capillary tube 400 depending upon a direction of the flow of refrigerant through capillary tube 400.

Capillary tube 400 includes a generally tubular body, such as a copper or aluminum pipe. Capillary tube 400 may be constructed in the same or similar manner to capillary tube 200 (FIG. 4). Thus, capillary tube 400 extends between a first end portion 402 and a second end portion 404 and defines an interior volume 406 for directing the flow of refrigerant through capillary tube 400.

Capillary tube 400 also includes a fixed restriction orifice 410 positioned at or adjacent first end portion 402 of capillary tube 400. Fixed restriction orifice 410 may be a cylindrical disk that defines an opening 412 having a smaller cross-sectional area than an adjacent or contiguous cross-sectional area of interior volume 406 of capillary tube 400. As may be seen in FIG. 4, interior volume 406 of capillary tube 400 may have a generally constant cross-sectional area between first and second end portions 402, 404 of capillary tube 400.

By providing fixed restriction orifice 410 with opening 412 at first end portion 402 of capillary tube 400, fixed restriction orifice 410 can adjust the restriction on the flow of refrigerant through capillary tube 400 depending upon a direction of the flow of refrigerant through capillary tube 400, e.g., in the same or similar manner to block 210 (FIG. 3) described above. For example, because opening 412 of fixed restriction orifice 410 has a smaller cross-sectional area than the cross-sectional area of interior volume 406 of capillary tube 400 at first end portion 402 of capillary tube 400, the restriction on the flow of refrigerant when sealed system 120 is operating in the heating mode is greater than when sealed system 120 is operating in the cooling mode.

Fixed restriction orifice 410 may be formed of or within any suitable material. For example, fixed restriction orifice 410 may be formed of a common material as capillary tube 400, such as copper or aluminum. Fixed restriction orifice 410 may also be mounted to capillary tube 400 and/or exterior coil 126 (FIG. 2). As an example, fixed restriction orifice 410 may be brazed or interference fit onto capillary tube 400 at first end portion 402 of capillary tube 400. As another example, fixed restriction orifice 410 may be brazed or interference fit onto a jumper tube of exterior coil 126.

FIG. 6 provides a perspective view of a capillary tube 500 according still another exemplary embodiment of the present subject matter. Capillary tube 500 may be used in any suitable heat pump system. For example, capillary tube 500 may be used in packaged terminal air conditioner unit 100 as capillary tube 128 of sealed system 120 (FIG. 2). As discussed in greater detail below, capillary tube 500 includes features for adjusting a restriction on a flow of refrigerant through capillary tube 500 depending upon a direction of the flow of refrigerant through capillary tube 500.

Capillary tube 500 includes a generally tubular body, such as a copper or aluminum pipe. Capillary tube 500 may be constructed in the same or similar manner to capillary tube 200 (FIG. 4). Thus, capillary tube 500 extends between a first end portion 502 and a second end portion 504 and defines an interior volume (not shown) for directing the flow of refrigerant through capillary tube 500.

Capillary tube 500 also includes a plurality of coils 510 defined by capillary tube 500 at or adjacent first end portion 502 of capillary tube 500. Coils 510 are formed by or with capillary tube 500. The interior volume of capillary tube 500 may have a generally constant cross-sectional area between first and second end portions 502, 504 of capillary tube 500 including coils 510.

By changing the direction of refrigerant within capillary tube 500, coils 510 can adjust the restriction on the flow of refrigerant through capillary tube 500 depending upon a direction of the flow of refrigerant through capillary tube 500, e.g., in the same or similar manner to block 210 (FIG. 3) described above. For example, due to the flow path for refrigerant provided by coils 510, the restriction on the flow of refrigerant when sealed system 120 is operating in the heating mode is greater than when sealed system 120 is operating in the cooling mode.

Coils 510 may be formed in any suitable manner on capillary tube 500. For example, a clamp or roller may plastically deform capillary tube 500 in order to form coils 510 at first end portion 502 of capillary tube 500. Coils 510 may include any suitable number of coils. For example, coils 510 may include at least two coils, at least three coils, at least five coils, at least ten coils, etc.

As may be seen in FIG. 4, capillary tube 500 defines a length L between first and second end portions 502, 504 of capillary tube 500. Coils 510 also define a length OL on capillary tube 500. The length OL of coils 510 may be less than the length L of capillary tube 500. For example, the length OL of coils 510 may be no greater than a quarter of the length L of capillary tube 500. As another example, the length OL of coils 510 may be no greater than a tenth of the length L of capillary tube 500.

FIG. 7 provides a perspective view of a capillary tube 600 according yet another exemplary embodiment of the present subject matter. FIGS. 8 and 9 provide partial section views capillary tube 600 and a flow washer 610 of capillary tube 600. Capillary tube 600 may be used in any suitable heat pump system. For example, capillary tube 600 may be used in packaged terminal air conditioner unit 100 as capillary tube 128 of sealed system 120 (FIG. 2). As discussed in greater detail below, capillary tube 600 includes features for adjusting a restriction on a flow of refrigerant through capillary tube 600 depending upon a direction of the flow of refrigerant through capillary tube 600.

Capillary tube 600 includes a generally tubular body, such as a copper or aluminum pipe. Capillary tube 600 may be constructed in the same or similar manner to capillary tube 200 (FIG. 4). Thus, capillary tube 600 extends between a first end portion 602 and a second end portion 604 and defines an interior volume 606 for directing the flow of refrigerant through capillary tube 600.

Capillary tube 600 also includes a flow washer 610 positioned within interior volume 606 of capillary tube 600 at or adjacent first end portion 602 of capillary tube 600. Flow washer 610 is deformable or moveable between various configurations that adjust a size of an opening 612 of flow washer 610. For example, as shown in FIG. 8, opening 612 of flow washer 610 has a first size when refrigerant is flowing in a first direction through interior volume 606 of capillary tube 600. As another example, as shown in FIG. 9, opening 612 of flow washer 610 has a second size when refrigerant is flowing in a second direction through interior volume 606 of capillary tube 600. The first size is different than the second size. For example, the first size may be larger than the second size. Thus, the size of opening 612 of flow washer 610 changes depending upon the direction of refrigerant flow through capillary tube 600. Flow washer 610 may elastically deform or actuate in any other suitable manner in order to adjust the size of opening 612 of flow washer 610 when the direction of refrigerant flow through capillary tube 600 changes.

By changing the size of opening 612 of flow washer 610, flow washer 610 can adjust the restriction on the flow of refrigerant through capillary tube 600 depending upon a direction of the flow of refrigerant through capillary tube 600, e.g., in the same or similar manner to block 210 (FIG. 3) described above. For example, by changing the size of opening 612 of flow washer 610, the restriction on the flow of refrigerant when sealed system 120 is operating in the heating mode is greater than when sealed system 120 is operating in the cooling mode. Flow washer 610 may be formed of any suitable material. For example, flow washer 610 may be formed with an elastically deformable material, such as rubber.

FIG. 10 provides a section view of a capillary tube 700 according yet another additional exemplary embodiment of the present subject matter. Capillary tube 700 may be used in any suitable heat pump system. For example, capillary tube 700 may be used in packaged terminal air conditioner unit 100 as capillary tube 128 of sealed system 120 (FIG. 2). As discussed in greater detail below, capillary tube 700 includes features for adjusting a restriction on a flow of refrigerant through capillary tube 700 depending upon a direction of the flow of refrigerant through capillary tube 700.

Capillary tube 700 includes a generally tubular body, such as a copper or aluminum pipe. Capillary tube 700 may be constructed in the same or similar manner to capillary tube 200 (FIG. 4). Thus, capillary tube 700 extends between a first end portion 702 and a second end portion 704 and defines an interior volume 706 for directing the flow of refrigerant through capillary tube 700.

Capillary tube 700 also includes a plurality of conical segments 710 defined by an inner surface 708 at or adjacent first end portion 702 of capillary tube 700. Conical segments 710 are formed by capillary tube 700 such that each conical segment of conical segments 710 successively reduces the cross-sectional area of interior volume 706 of capillary tube 700 at conical segments 710. Thus, each conical segment of conical segments 3710 may expand along an axial direction A defined between first and second end portions 702, 704 of capillary tube 700. As may be seen in FIG. 4, interior volume 706 of capillary tube 700 may have a generally constant cross-sectional area between first and second end portions 702, 704 of capillary tube 700 except for conical segments 710.

By sequentially reducing the cross-sectional area of interior volume 706 of capillary tube 700 at first end portion 702 of capillary tube 700, conical segments 710 can adjust the restriction on the flow of refrigerant through capillary tube 700 depending upon a direction of the flow of refrigerant through capillary tube 700, e.g., in the same or similar manner to block 210 (FIG. 3) described above. For example, by sequentially reducing the cross-sectional area of interior volume 706 of capillary tube 700 at first end portion 702 of capillary tube 700, the restriction on the flow of refrigerant when sealed system 120 is operating in the heating mode is greater than when sealed system 120 is operating in the cooling mode.

Conical segments 710 may include any suitable number of conical segments. For example, conical segments 710 may include at least two conical segments, at least three conical segments, at least five conical segments, at least ten conical segments, etc. It should be understood that segments 710 may have any other suitable expanding cross-sectional shape in alternative exemplary embodiments. For example, segments 710 may have a frustoconical shape.

As may be seen in FIG. 10, capillary tube 700 defines a length L between first and second end portions 702, 704 of capillary tube 700. Conical segments 710 also define a length SL on capillary tube 700. The length SL of conical segments 710 may be less than the length L of capillary tube 700. For example, the length SL of conical segments 710 may be no greater than a quarter of the length L of capillary tube 700. As another example, the length SL of conical segments 710 may be no greater than a tenth of the length L of capillary tube 700.

FIGS. 11 and 12 provide schematic views of a capillary tube 800 according still yet another additional exemplary embodiment of the present subject matter. Capillary tube 800 may be used in any suitable heat pump system. For example, capillary tube 800 may be used in packaged terminal air conditioner unit 100 as capillary tube 128 of sealed system 120 (FIG. 2). As discussed in greater detail below, capillary tube 800 includes features for adjusting a restriction on a flow of refrigerant through capillary tube 800 depending upon a direction of the flow of refrigerant through capillary tube 800.

Capillary tube 800 includes a generally tubular body, such as a copper or aluminum pipe. Capillary tube 800 may be constructed in the same or similar manner to capillary tube 200 (FIG. 4). Thus, capillary tube 800 extends between a first end portion 802 and a second end portion 804 and defines an interior volume 806 for directing the flow of refrigerant through capillary tube 800.

Capillary tube 800 also includes a piston 810 slidably or movably disposed within interior volume 806 of capillary tube 800 at first end portion 802 of capillary tube 800. In particular, piston 810 is slidable within interior volume 806 between a first position (FIG. 11) and a second position (FIG. 12). Piston 810 obstructs more refrigerant flow through interior volume 806 of capillary tube 800 in the first position than in the second position. For example, piston 810 may define a plurality of channels 812 therein. When piston 810 is in the first position as shown in FIG. 11, refrigerant may flow through all of channels 812. Conversely, at least one of channels 812 is blocked or obstructed when piston 810 is in the second position as shown in FIG. 12.

By moving between the first and second positions, piston 810 can adjust the restriction on the flow of refrigerant through capillary tube 800 depending upon a direction of the flow of refrigerant through capillary tube 800, e.g., in the same or similar manner to block 210 (FIG. 3) described above. For example, by moving between the first and second positions, the restriction on the flow of refrigerant when sealed system 120 is operating in the heating mode is greater than when sealed system 120 is operating in the cooling mode.

FIG. 13 provides a perspective view of a capillary tube 900 according an additional exemplary embodiment of the present subject matter. FIGS. 14 and 15 provide section views of capillary tube 900. Capillary tube 900 may be used in any suitable heat pump system. For example, capillary tube 900 may be used in packaged terminal air conditioner unit 100 as capillary tube 128 of sealed system 120 (FIG. 2). As discussed in greater detail below, capillary tube 900 includes features for adjusting a restriction on a flow of refrigerant through capillary tube 900 depending upon a direction of the flow of refrigerant through capillary tube 900.

Capillary tube 900 includes a generally tubular body, such as a copper or aluminum pipe. Capillary tube 900 may be constructed in the same or similar manner to capillary tube 200 (FIG. 4). Thus, capillary tube 900 extends between a first end portion 902 and a second end portion 904 and defines an interior volume 906 for directing the flow of refrigerant through capillary tube 900.

As may be seen in FIGS. 14 and 15, interior volume 906 of capillary tube 900 may have a varying or expanding cross-sectional area between first and second end portions 902, 904 of capillary tube 900. As shown in FIG. 15, capillary tube 900 may also define a chamber 910 at or adjacent first end portion 902 of capillary tube 900. Thus, the cross-sectional area of interior volume 906 of capillary tube 900 may uniformly vary or expand along a length L of capillary tube 900.

By varying the cross-sectional area of interior volume 906 of capillary tube 900 between first and second end portions 902, 904 of capillary tube 900, conical segments 910 can adjust the restriction on the flow of refrigerant through capillary tube 900 depending upon a direction of the flow of refrigerant through capillary tube 900, e.g., in the same or similar manner to block 210 (FIG. 3) described above. For example, by varying the cross-sectional area of interior volume 906 of capillary tube 900 between first and second end portions 902, 904 of capillary tube 900, the restriction on the flow of refrigerant when sealed system 120 is operating in the heating mode is greater than when sealed system 120 is operating in the cooling mode.

FIGS. 16 and 17 provide section views of capillary tube 900 with another internal configuration for adjusting the restriction on the flow of refrigerant through capillary tube 900 depending upon a direction of the flow of refrigerant through capillary tube 900. As may be seen in FIGS. 16 and 7, capillary tube 900 may define a plurality of channels 920 therein, e.g., that extend between first and second end portions 902, 904 of capillary tube 900. A plug or bung 922 is movably disposed within chamber 910. Bung 922 is rollable within interior volume 806 between a first position (FIG. 16) and a second position (FIG. 17). Bung 922 obstructs at least one of passages 920 when bung 922 is in the first position. Conversely, bung 922 not block any of passages 920 or block the one of passages to a less degree when bung 922 is in the second position.

By moving between the first and second positions, bung 922 can adjust the restriction on the flow of refrigerant through capillary tube 900 depending upon a direction of the flow of refrigerant through capillary tube 900, e.g., in the same or similar manner to block 210 (FIG. 3) described above. For example, by moving between the first and second positions, the restriction on the flow of refrigerant when sealed system 120 is operating in the heating mode is greater than when sealed system 120 is operating in the cooling mode.

Any suitable methods may be used to form capillary tube 900. For example, capillary tube 900 may be fabricated as a unitary capillary tube, e.g., such that capillary tube 900 is formed of a single continuous piece of metal, plastic or other suitable material. More particularly, capillary tube 900 may be manufactured or formed using an additive process, such as Fused Deposition Modeling (FDM), Selective Laser Sintering (SLS), Stereolithography (SLA), Digital Light Processing (DLP) and other known processes. An additive process fabricates metal or plastic components using three-dimensional information, for example a three-dimensional computer model, of the component. The three-dimensional information is converted into a plurality of slices, each slice defining a cross section of the component for a predetermined height of the slice. The component is then “built-up” slice by slice, or layer by layer, until finished.

Accordingly, three-dimensional information of capillary tube 900 may be determined. As an example, a model or prototype of capillary tube 900 may be scanned to determine the three-dimensional information of capillary tube 900. As another example, a model of capillary tube 900 may be constructed using a suitable CAD program to determine the three-dimensional information of capillary tube 900. The three-dimensional information may then be converted into a plurality of slices that each defines a cross-sectional layer of capillary tube 900. As an example, the three-dimensional information may be divided into equal sections or segments, e.g., along a central axis of capillary tube 900 or any other suitable axis. Thus, the three-dimensional information may be discretized in order to provide planar cross-sectional layers of capillary tube 900.

Capillary tube 900 may then be fabricated using the additive process, or more specifically each layer is successively formed, e.g., by fusing or polymerizing a metal or plastic using laser energy or heat. The layers may have any suitable size. For example, each layer may have a size between about five ten-thousandths of an inch and about one thousandths of an inch. Capillary tube 900 may be fabricated using any suitable additive manufacturing machine. For example, any suitable laser sintering machine, inkjet printer or laserjet printer may be used.

Utilizing additive manufacturing, capillary tube 900 may have fewer components and/or joints than known capillary tubes. Specifically, capillary tube 900 may require fewer components because capillary tube 900 may be a single piece of continuous metal or plastic, e.g., rather than multiple pieces of metal or plastic joined or connected together. Also, the shape, contour and features of capillary tube 900 described above may be formed using such methods. As a result, capillary tube 900 may provide improved efficiency for a heat pump system, such as sealed system 120, by adjusting the restriction on the flow of refrigerant through capillary tube 900 depending upon a direction of the flow of refrigerant through capillary tube 900. Also, capillary tube 900 may be less prone to leaks and/or be stronger when formed with additive processes. It should be understood that other capillary tubes, such as capillary tube 200 (FIG. 3), capillary tube 300 (FIG. 4), capillary tube 400 (FIG. 5), capillary tube 500 (FIG. 6), capillary tube 600 (FIG. 7), capillary tube 700 (FIG. 10) and/or capillary tube 800 (FIG. 11), may also be manufactured or formed using the addictive processes described above.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. A packaged terminal air conditioner unit, comprising: a casing extending between an exterior side portion and an interior side portion; a compressor positioned within the casing, the compressor operable to compress a refrigerant; an interior coil positioned within the casing at the interior side portion of the casing; an exterior coil positioned within the casing at the exterior side portion of the casing; a reversing valve in fluid communication with the compressor in order to receive compressed refrigerant from the compressor, the reversing valve configured for selectively directing the compressed refrigerant from the compressor to either the interior coil or the exterior coil; a capillary tube extending between the interior coil and the exterior coil in order to direct refrigerant between the interior coil and the exterior coil, the capillary tube comprising means for adjusting a restriction on a flow of refrigerant through the capillary tube depending upon a direction of the flow of refrigerant through the capillary tube.
 2. The packaged terminal air conditioner unit of claim 1, wherein the capillary tube extends between a first end portion and a second end portion, the first end portion of the capillary tube positioned adjacent the exterior coil, the second end portion of the capillary tube positioned adjacent the interior coil, the capillary tube defining an interior volume for directing the flow of refrigerant through the capillary tube, the means for adjusting the restriction comprising a wire positioned within the interior volume of the capillary tube at the first end portion of the capillary tube.
 3. The packaged terminal air conditioner unit of claim 2, wherein the wire is mounted to the capillary tube at the first end portion of the capillary tube.
 4. The packaged terminal air conditioner unit of claim 2, wherein the capillary tube and the wire are bent at the first end portion of the capillary tube in order to hinder movement of the wire within the interior volume of the capillary tube.
 5. The packaged terminal air conditioner unit of claim 2, wherein the capillary tube and the wire are constructed of copper.
 6. The packaged terminal air conditioner unit of claim 1, wherein the capillary tube extends between a first end portion and a second end portion, the first end portion of the capillary tube positioned adjacent the exterior coil, the second end portion of the capillary tube positioned adjacent the interior coil, the means for adjusting the restriction comprising a crimp defined by the capillary tube at the first end portion of the capillary tube.
 7. The packaged terminal air conditioner unit of claim 1, wherein the capillary tube extends between a first end portion and a second end portion, the first end portion of the capillary tube positioned adjacent the exterior coil, the second end portion of the capillary tube positioned adjacent the interior coil, the means for adjusting the restriction comprising a fixed restriction orifice positioned at the first end portion of the capillary tube.
 8. The packaged terminal air conditioner unit of claim 7, wherein the fixed restriction orifice is brazed or interference fit onto the capillary tube at the first end portion of the capillary tube.
 9. The packaged terminal air conditioner unit of claim 7, wherein the fixed restriction orifice is brazed or interference fit onto a jumper tube of the exterior coil.
 10. The packaged terminal air conditioner unit of claim 1, wherein the capillary tube extends between a first end portion and a second end portion, the first end portion of the capillary tube positioned adjacent the exterior coil, the second end portion of the capillary tube positioned adjacent the interior coil, the means for adjusting the restriction comprising a plurality of coils defined by the capillary tube at the first end portion of the capillary tube.
 11. The packaged terminal air conditioner unit of claim 1, wherein the capillary tube extends between a first end portion and a second end portion, the first end portion of the capillary tube positioned adjacent the exterior coil, the second end portion of the capillary tube positioned adjacent the interior coil, the capillary tube defining an interior volume for directing the flow of refrigerant through the capillary tube, the means for adjusting the restriction comprising a flow washer positioned within the interior volume of the capillary tube at the first end portion of the capillary tube.
 12. The packaged terminal air conditioner unit of claim 1, wherein the capillary tube extends between a first end portion and a second end portion, the first end portion of the capillary tube positioned adjacent the exterior coil, the second end portion of the capillary tube positioned adjacent the interior coil, the capillary tube defining an interior volume for directing the flow of refrigerant through the capillary tube, the means for adjusting the restriction comprising a plurality of conical segments defined by an inner surface of the capillary tube proximate at the first end portion of the capillary tube.
 13. The packaged terminal air conditioner unit of claim 12, wherein each conical segment of the plurality of conical segments expands along an axial direction defined between the first and second end portions of the capillary tube.
 14. The packaged terminal air conditioner unit of claim 1, wherein the capillary tube extends between a first end portion and a second end portion, the first end portion of the capillary tube positioned adjacent the exterior coil, the second end portion of the capillary tube positioned adjacent the interior coil, the capillary tube defining an interior volume for directing the flow of refrigerant through the capillary tube, the means for adjusting the restriction comprising a piston disposed within the interior volume of the capillary tube at the first end portion of the capillary tube, the piston slidable within the interior volume between a first position and a second position, the piston obstructing more refrigerant flow through the interior volume of the capillary tube in the first position than in the second position.
 15. A packaged terminal air conditioner unit, comprising: a casing; a compressor positioned within the casing, the compressor operable to increase a pressure of a refrigerant; a reversing valve positioned within the casing, the reversing valve in fluid communication with the compressor in order to receive compressed refrigerant from the compressor; an interior coil positioned within the casing; an exterior coil positioned within the casing opposite the interior coil, the interior coil and the exterior coil in fluid communication with the reversing valve such that either the interior coil or the exterior coil receive the compressed refrigerant from the reversing valve; and a capillary tube extending between the interior coil and the exterior coil in order to direct refrigerant between the interior coil and the exterior coil, the capillary tube extending between a first end portion and a second end portion, the first end portion of the capillary tube positioned adjacent the exterior coil, the second end portion of the capillary tube positioned adjacent the interior coil, the capillary tube defining an interior volume for directing the flow of refrigerant through the capillary tube; and a block positioned within the interior volume of the capillary tube at the first end portion of the capillary tube such that the block occupies a portion of the interior volume of the tubular body at the first end portion of the tubular body.
 16. The packaged terminal air conditioner unit of claim 15, wherein the block is mounted to the capillary tube at the first end portion of the capillary tube.
 17. The packaged terminal air conditioner unit of claim 15, wherein the capillary tube and the block are bent at the first end portion of the capillary tube in order to hinder movement of the block within the interior volume of the capillary tube.
 18. The packaged terminal air conditioner unit of claim 15, wherein the capillary tube and the block are constructed of copper.
 19. The packaged terminal air conditioner unit of claim 15, wherein the capillary tube is constructed of a first material and the block is constructed of a second material, the first and second material being different.
 20. A capillary tube for a heat pump system, comprising: a tubular body extending between a first end portion and a second end portion, the tubular body defining an interior volume for directing a flow of refrigerant through the tubular body, cross-sections of the interior volume of the tubular body being substantially constant between the first and second end portions of the tubular body; a block positioned within the interior volume of the tubular body at the first end portion of the tubular body such that the block occupies a portion of the interior volume of the tubular body at the first end portion of the tubular body. 